Lucene:精确匹配不会首先显示

Question

我使用演示IndexFiles和SearchFiles类来索引和搜索org.apache.lucene.demo包中的内容。

我的问题是，当我使用一个包含多个单词的查询时，我得不到与之完全匹配的结果。例如：

Enter query:
"natural language"
Searching for: "natural language"
298 total matching documents
1. download\researchers.uq.edu.au\fields-of-research\natural-language-processing
.txt
2. download\researchers.uq.edu.au\research-project\16267.txt
3. download\researchers.uq.edu.au\research-project\16279.txt
4. download\researchers.uq.edu.au\research-project\18361.txt
5. download\www.uq.edu.au\news\%3Farticle%3D2187.txt
6. download\researchers.uq.edu.au\researcher\2115.txt
7. download\ceit.uq.edu.au\content\2013-2014-summer-research-scholarship-project
s-dr-alan-cody%3Fpage%3D1.txt
8. download\ceit.uq.edu.au\content\2013-2014-summer-research-scholarship-project
s-dr-alan-cody%3Fpage%3D2.txt
9. download\ceit.uq.edu.au\content\2013-2014-summer-research-scholarship-project
s-dr-alan-cody.txt
10. download\www.ceit.uq.edu.au\content\2013-2014-summer-research-scholarship-pr
ojects-dr-alan-cody.txt
Press (n)ext page, (q)uit or enter number to jump to a page.

的结果与以下内容不同：

Enter query:
natural language
Searching for: natural language
54307 total matching documents
1. download\cyberschool.library.uq.edu.au\display_resource.phtml%3Frid%3D190.txt

2. download\cyberschool.library.uq.edu.au\display_resource.phtml%3Frid%3D576.txt

3. download\cyberschool.library.uq.edu.au\display_resource.phtml%3Frid%3D46.txt
4. download\espace.library.uq.edu.au\view\UQ%3A166163.txt
5. download\cyberschool.library.uq.edu.au\display_resource.phtml%3Frid%3D108.txt

6. download\cyberschool.library.uq.edu.au\display_resource.phtml%3Frid%3D70.txt
7. download\cyberschool.library.uq.edu.au\display_resource.phtml%3Frid%3D708.txt

8. download\researchers.uq.edu.au\fields-of-research\natural-language-processing
.txt
9. download\researchers.uq.edu.au\research-project\16267.txt
10. download\cyberschool.library.uq.edu.au\display_resource.phtml%3Frid%3D117.tx
t
Press (n)ext page, (q)uit or enter number to jump to a page.

例如，第一个匹配文档甚至不包含"language“关键字。

如果我在IndexSearcher类中使用explain()方法，那么我将得到第一个结果：

1. download\cyberschool.library.uq.edu.au\display_resource.phtml%3Frid%3D190.txt
0.70643383 = (MATCH) sum of:
  0.5590494 = (MATCH) weight(contents:natural in 62541) [DefaultSimilarity], result of:
    0.5590494 = score(doc=62541,freq=4.0 = termFreq=4.0
), product of:
      0.8091749 = queryWeight, product of:
        4.4216847 = idf(docFreq=13111, maxDocs=401502)
        0.18300149 = queryNorm
      0.6908882 = fieldWeight in 62541, product of:
        2.0 = tf(freq=4.0), with freq of:
          4.0 = termFreq=4.0
        4.4216847 = idf(docFreq=13111, maxDocs=401502)
        0.078125 = fieldNorm(doc=62541)
  0.1473844 = (MATCH) weight(contents:language in 62541) [DefaultSimilarity], result of:
    0.1473844 = score(doc=62541,freq=1.0 = termFreq=1.0
), product of:
      0.5875679 = queryWeight, product of:
        3.2107275 = idf(docFreq=44012, maxDocs=401502)
        0.18300149 = queryNorm
      0.25083807 = fieldWeight in 62541, product of:
        1.0 = tf(freq=1.0), with freq of:
          1.0 = termFreq=1.0
        3.2107275 = idf(docFreq=44012, maxDocs=401502)
        0.078125 = fieldNorm(doc=62541)

如果我单击“下一步”并找到如下结果：

19. download\www.uq.edu.au\news\%3Farticle%3D2187.txt
0.47449595 = (MATCH) sum of:
  0.2795247 = (MATCH) weight(contents:natural in 35173) [DefaultSimilarity], result of:
    0.2795247 = score(doc=35173,freq=4.0 = termFreq=4.0
), product of:
      0.8091749 = queryWeight, product of:
        4.4216847 = idf(docFreq=13111, maxDocs=401502)
        0.18300149 = queryNorm
      0.3454441 = fieldWeight in 35173, product of:
        2.0 = tf(freq=4.0), with freq of:
          4.0 = termFreq=4.0
        4.4216847 = idf(docFreq=13111, maxDocs=401502)
        0.0390625 = fieldNorm(doc=35173)
  0.19497125 = (MATCH) weight(contents:language in 35173) [DefaultSimilarity], result of:
    0.19497125 = score(doc=35173,freq=7.0 = termFreq=7.0
), product of:
      0.5875679 = queryWeight, product of:
        3.2107275 = idf(docFreq=44012, maxDocs=401502)
        0.18300149 = queryNorm
      0.33182758 = fieldWeight in 35173, product of:
        2.6457512 = tf(freq=7.0), with freq of:
          7.0 = termFreq=7.0
        3.2107275 = idf(docFreq=44012, maxDocs=401502)
        0.0390625 = fieldNorm(doc=35173)

该页面本身包含确切的关键字“自然语言”。所以我的问题是：

1)为什么Lucene没有首先显示完全匹配？

2)为什么Lucene显示的结果甚至不包含关键字？

3)在哪里/如何更改它，使其首先显示完全匹配的项，然后显示更相关的项？

Answer 1

1-它不是故意的。请参阅Lucene query syntax上的文档。查询natural language是由两个术语组成的查询。就它们本身而言，Lucene并不偏爱将术语紧密地放在一起。如果您想要找到精确匹配，短语查询是正确的方法，如"natural language"

2-包含解释的两个结果都包含两个术语的匹配项，请参见：

0.2795247 = (MATCH) weight(contents:natural in 35173) [DefaultSimilarity], result of:
  0.2795247 = score(doc=35173,freq=4.0 = termFreq=4.0
...
0.19497125 = (MATCH) weight(contents:language in 35173) [DefaultSimilarity], result of:
  0.19497125 = score(doc=35173,freq=7.0 = termFreq=7.0

根据Lucene的说法，它在该文档中找到了4次"natural“，在content字段(我假设这是您的默认字段)中找到了7次"language”。

3-查看查询解析器的语法，看看什么对你最有意义。听起来你可能会发现Proximity Searches很有用。

如果您只是想简单地获得短语匹配，后面紧跟着其他短语，那么您可以使用类似以下内容：

"natural language" natural language